Organic el display panel and production method therefor

ABSTRACT

An organic electroluminescence (EL) display panel having pixels arranged in a matrix of rows and columns includes: a substrate; pixel electrode layers that are made of a light-reflective material and are arranged on the substrate in the matrix; an insulating layer that is provided above the substrate and the pixel electrode layers; organic functional layers that are provided above the pixel electrode layers; and a light-transmissive counter electrode layer that is provided above the organic functional layers, wherein the insulating layer has a first opening and second openings for each of the pixel electrode layers, the first opening being elongated in a column direction, the second openings each being shorter than the first opening in the column direction and being lined up adjacent to the first opening, and the organic functional layers include light-emitting layers in which organic electroluminescence occurs in the first opening and the second openings.

TECHNICAL FIELD

The present disclosure relates to organic electroluminescence (EL)display panels that use organic EL elements employingelectroluminescence of organic material, and to a method ofmanufacturing the same.

BACKGROUND ART

In recent years, organic EL display panels including a matrix of organicEL elements arranged above a substrate have been put into practical use,as display panels for use in display devices such as digitaltelevisions. Such organic EL display panels achieve high visibility dueto the organic EL elements being self-luminous. In the organic ELdisplay panels, each organic EL element has a basic configuration inwhich a light emitting layer containing an organic light emittingmaterial is disposed between an electrode pair of an anode and acathode, and when driven, a voltage is applied between the electrodepair and light is emitted through recombination of holes injected to thelight emitting layer from the anode and electrons injected to the lightemitting layer from the cathode.

In the organic EL display panels, there has been a demand for improvinga light extraction efficiency of the organic EL elements from thestandpoint of reducing power consumption, increasing the panel servicelife, and so on.

In response to this demand, display devices proposed in PatentLiteratures 1 and 2 for example include: a reflector (reflectivestructure), which is constituted from first members of a concave shapeand second members that are each placed between two adjacent firstmembers; and an organic light emitting layer, which is provided betweenthe first members and the second members. The proposed display devicesexhibit an improved light extraction efficiency owing to the firstmembers and the second members having refractive indices within apredetermined range.

CITATION LIST Patent Literature [Patent Literature 1]

-   -   Japanese Patent Application Publication No. 2013-191533

[Patent Literature 2]

-   -   Japanese Patent Application Publication No. 2015-144107

[Patent Literature 3]

-   -   Japanese Patent Application Publication No. 2013-240733

SUMMARY Technical Problem

According to the techniques described in Patent Literatures 1 and 2,however, when a low-cost ink application method such as an ink jetmethod (Patent Literature 3 for example) is used for constituting areflector including organic light emitting layers, failure sometimesoccurs such as an insufficient ink spread. This is due to the concavefirst members that are provided on surfaces of pixel electrodes ontowhich an ink containing light emitting layer materials is to be applied.Such an insufficient ink spread results in difficulties in performinguniform ink application in each pixel, and thus film thickness of theformed light emitting layer is ununiform within the pixel. This causes aproblem that film thickness of the formed light emitting layers isununiform within the pixel, and thus luminance unevenness occurs, andluminous efficiency and panel service life deteriorate.

The present disclosure was made in view of the above problem, and aimsto provide an organic EL display panel and a manufacturing method of thesame that maintain a high luminous efficiency and uniformize filmthickness of light emitting layers in each pixel to suppress luminanceunevenness, with a low-cost ink application method for a reflectorhaving a high light extraction efficiency.

Solution

One aspect of the present disclosure provides an organicelectroluminescence (EL) display panel including pixels arranged in amatrix of rows and columns, the organic EL display panel comprising: asubstrate; pixel electrode layers that are made of a light-reflectivematerial and are arranged on the substrate in the matrix; an insulatinglayer that is provided above the substrate and the pixel electrodelayers; organic functional layers that are provided above the pixelelectrode layers; and a light-transmissive counter electrode layer thatis provided above the organic functional layers, wherein the insulatinglayer has a first opening and second openings for each of the pixelelectrode layers, the first opening being elongated in a columndirection, the second openings each being shorter than the first openingin the column direction and being lined up adjacent to the firstopening, and the organic functional layers include light emitting layersin which organic electroluminescence occurs in the first opening and thesecond openings.

Advantageous Effects

According to the organic EL display panel and the manufacturing methodof the same relating to the one aspect of the present disclosure, it ispossible to maintain a high luminous efficiency and uniformize filmthickness of light emitting layers in each pixel to suppress luminanceunevenness in an organic display panel having a reflector includingapplication-type functional layers.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic block diagram of circuit configuration of anorganic EL display device 1 relating to an embodiment of the presentdisclosure.

FIG. 2 is a schematic circuit diagram of circuit configuration of eachsubpixel 100 se of an organic EL display panel 10 used in the organic ELdisplay device 1.

FIG. 3 is a schematic plan view of part of the organic EL display panel10.

FIG. 4A is an enlarged plan view of a portion X1 in FIG. 3, FIG. 4B isan enlarged plan view of the portion X1 viewed from above an insulatinglayer 122, and FIG. 4C is a schematic cross-sectional view of an openingtaken along a line B2-B2 in FIG. 4B.

FIG. 5 is a perspective view from an oblique angle above a portion ofthe insulating layer 122 corresponding to a subpixel 100 se of anorganic EL element 100.

FIG. 6 is a schematic cross-sectional view taken along a line A1-A1 inFIG. 4B.

FIG. 7 is a schematic cross-sectional view taken along a line B1-B1 inFIG. 4B.

FIGS. 8A to 8E are schematic cross-sectional views of the organic ELdisplay panel 10 during manufacture, taken along a line at the sameposition as the line A1-A1 in FIG. 4B.

FIGS. 9A to 9C are schematic cross-sectional views of the organic ELdisplay panel 10 during manufacture, taken along a line at the sameposition as the line A1-A1 in FIG. 4B.

FIGS. 10A to 10C are schematic cross-sectional views of the organic ELdisplay panel 10 during manufacture, taken along a line at the sameposition as the line A1-A1 in FIG. 4B.

FIGS. 11A and 11B are schematic cross-sectional views of the organic ELdisplay panel during manufacture, taken along a line at the sameposition as the line A1-A1 in FIG. 4B, showing bonding of a CF substrate131 to a rear panel.

FIGS. 12A to 12D are schematic cross-sectional views of the organic ELdisplay panel 10 during manufacture, taken along a line at the sameposition as the line B1-B1 in FIG. 4B.

FIGS. 13A to 13D are schematic cross-sectional views of the organic ELdisplay panel 10 during manufacture, taken along a line at the sameposition as the line B1-B1 in FIG. 4B.

FIGS. 14A and 14B are schematic cross-sectional views of the organic ELdisplay panel 10 during manufacture, taken along a line at the sameposition as the line B1-B1 in FIG. 4B, showing bonding of the CFsubstrate 131 to the rear panel.

FIG. 15 is a schematic view of the organic EL display panel 10 duringmanufacture, showing a process of applying inks for light emitting layerformation to regions of a lattice shape above a substrate that aredefined by insulating sublayers 122X and 122Y.

FIGS. 16A to 16F are schematic cross-sectional views of the organic ELdisplay panel 10 during manufacture, showing manufacturing of the CFsubstrate 131.

FIG. 17 shows measurement results of ink spread rate and calculatedvalues of luminance magnification with respect to light emitting layersin subpixels in organic EL display panels relating to examples.

FIGS. 18A to 18H are enlarged plan views of a subpixel relating to amodification.

FIGS. 19A and 19B are plan views of an insulating layer 922corresponding to a subpixel of an organic EL display panel relating tothe inventors' conception.

FIG. 20 shows measurement results of ink spread rate and calculatedvalues of luminance magnification with respect to light emitting layersin subpixels in the organic EL display panel relating to the inventors'conception.

DESCRIPTION OF EMBODIMENTS

<<Process by which One Aspect of the Present Disclosure was Achieved>>

The inventors considered a problem in manufacturing of organic ELdisplay panels (hereinafter referred to just as display panels). Thefollowing describes the problem with reference to the drawings.

According to the organic EL display devices described in PatentLiteratures 1 and 2, as described above, in the case where a low-costink application method such as an ink jet method is used for formingorganic light emitting layers, uniform ink application in each pixel isdifficult due to the concave first members, which are provided on thepixel electrodes onto which the ink containing light emitting layermaterials is to be applied. As a result, the ink insufficiently spreadsin the pixel, and this causes a problem that the film thickness of thelight emitting layers is ununiform and thus luminance unevenness occurs.

In response to this problem, the inventors performed a test with use oftheir conceived test display panel in order to suppress an insufficientink spread in each pixel during a manufacturing process. The followingprovides comparative description of a reflector of the inventors'conceived test display panel with a conventional reflector in terms oflight extraction efficiency and ink spread with reference to FIGS. 19A,19B, and 20.

FIGS. 19A and 19B are plan views of an insulating layer 922corresponding to a subpixel region 900 a of the display panel relatingto the inventors' conception.

FIG. 19A shows a subpixel with a reflector of the display panel wheretruncated conical openings 922 zA are provided in the insulating layer922 (the subpixel is hereinafter referred to as Sample A). Specifically,as shown in FIG. 19A, 48 openings 922 zA are provided such that threerows of openings 922 zA are arranged in regular intervals in anX-direction and 16 rows of openings 922 zA are arranged in regularintervals in a Y-direction. A region including the 48 openings 922 zAconstitutes a luminous region. The openings 922 zA of Sample A have awidth in a column direction and a width in a row direction that areequal to each other (1:1).

FIG. 19B shows a subpixel with a reflector of the display panel wherethree elongated openings 922 z, which extend in the Y-direction, arearranged in the insulating layer 922 (the subpixel is hereinafterreferred to as Sample B). The openings 922 z have a width in the columndirection 20 times a width in the row direction (20:1). Note thatSamples A and B are equal to each other in terms of pixel shape andsize.

First, evaluation of light extraction efficiency was performed bycalculation of luminance magnification of Samples A and B.

FIG. 20 shows, in a right column, calculated values of luminancemagnification for subpixels. The luminance magnification indicates aluminance value of each sample relative to that of planar subpixels ofthe same size with no reflector.

As shown in FIG. 20, while Sample A exhibits luminance magnification of1.6, Sample B exhibits luminance magnification of 1.4. It is true thatthe luminance magnification of Sample B is low compared with that ofSample A, but its ratio to that of Sample A is only approximate 1.4/1.6.Accordingly, the luminance magnification of Sample B is not low enoughto damage effects of the reflector.

This seems to be because of the following reason. The light extractionefficiency of the reflector increases with an increase in area of slopessurrounding the openings 922 z functioning as the reflective structure.Due to this, the light extraction efficiency increases with a decreasein difference between the width in the column direction and the width inthe row direction of the openings. Accordingly, Sample A functions as apreferable reflector and thus exhibits a high light extractionefficiency. Compared with this, Sample B has bars, which extend in therow direction in the insulating layer 922, only at both ends of thesubpixel in the column direction. Accordingly, Sample B has small-areaslopes extending in the row direction and thus exhibits a lower lightextraction efficiency than Sample A. On the other hand, Sample B islarger than Sample A both in terms of area of luminous region in thecolumn direction and area of slopes extending in the column direction.This seems to be the reason why the light extraction efficiency ofSample B is not impaired greatly.

Next, regarding the ink spread, the inventors performed a test offorming functional layers using inks of the same amount in order tomeasure an ink spread rate based on a ratio of an area of the functionallayers to an area of the subpixel region 900 a. FIG. 20 shows, in amiddle column, a measurement result of the ink spread rate for the lightemitting layers in the subpixels. As shown in FIG. 20, while Sample Aexhibits an ink spread rate of 24%, Sample B exhibits an ink spread rateof 75%, which is drastically higher than Sample A.

This seems to be because of the following reasons. In Sample A, thenumber and the area of the bars between the openings 922 zA are bothlarge, and this hinders the flow of the ink. Also, the area of theopenings 922 zA is small. Due to this, when an ink is dropped onto thesubpixel, air in the openings 922 zA cannot easily escape. This seems tobe the reason why the spread of the ink over the subpixel is difficultin Sample A. In Sample B compared with this, the openings 922 z havetherebetween no bar that hinders the flow of the ink in the columndirection, and thus the ink easily flows in the column direction.Further, the openings 922 z are elongated and extend in the columndirection. Due to this, air in the openings 922 z easily flows in thecolumn direction, and thus does not hinder the flow of the ink so much.This seems to be the reason why Sample B exhibits an ink spread rate,which is drastically higher than Sample A.

In view of the above test results, the inventors earnestly considered areflector that is capable of improving the light extraction efficiencyof organic EL elements and improving the ink spread rate in pixels in aprocess of applying an ink containing light emitting layer materials inthe pixels. As a result, the inventors conceived of the display paneldescribed in the embodiment of the present disclosure.

<<Aspects of the Present Disclosure>>

One aspect of the present disclosure provides an organicelectroluminescence (EL) display panel including pixels arranged in amatrix of rows and columns, the organic EL display panel comprising: asubstrate; pixel electrode layers that are made of a light-reflectivematerial and are arranged on the substrate in the matrix; an insulatinglayer that is provided above the substrate and the pixel electrodelayers; organic functional layers that are provided above the pixelelectrode layers; and a light-transmissive counter electrode layer thatis provided above the organic functional layers, wherein the insulatinglayer has a first opening and second openings for each of the pixelelectrode layers, the first opening being elongated in a columndirection, the second openings each being shorter than the first openingin the column direction and being lined up adjacent to the firstopening, and the organic functional layers include light emitting layersin which organic electroluminescence occurs in the first opening and thesecond openings.

With this configuration, it is possible to maintain a high luminousefficiency and uniformize film thickness of light emitting layers ineach pixel to suppress luminance unevenness, with a low-cost inkapplication method for a reflector.

Also, in the above aspect, for each of the pixels, an upper edge of awall of each of the second openings that is away from an outer edge ofthe pixel in a row direction may be lower in height than one of an upperedge of a wall of the first opening and an upper edge of a wall of eachof the second openings that are nearest the outer edge in the rowdirection.

With this configuration, the height of bars, which hinder an ink flow inthe row direction, is low, and this facilitates the ink flow in the rowdirection. Thus, an ink spreads in the first opening 122 z in the columndirection, and then further spreads therefrom in the row direction. As aresult, the ink spreads over the entire subpixel region 900 a. Thisuniformizes the film thickness of the light emitting layers in eachpixel to suppress luminance unevenness.

Also, in any of the above aspects, for each of the pixels, one of a wallof the first opening and a wall of each of the second openings that areaway from an outer edge of the pixel in a row direction may be larger ingradient than one of a wall of the first opening and a wall of each ofthe second openings that are nearest the outer edge in the rowdirection.

With this configuration, it is possible to improve the light extractionefficiency in the first openings 122 z on the inner side in thesubpixels 100 se, and increase the viewing angle in the first openings122 z on the nearest side to the outer edges of the subpixels 100 se,thereby to cause the light emitting layers 123 to efficiently emit lightupward.

Also, in any of the above aspects, the insulating layer may further havea third opening for each of the pixel electrode layers, the thirdopening being elongated in the column direction, the second openings maybe disposed between the first opening and the third opening in a rowdirection, an upper edge of a wall of the first opening that is adjacentto the second openings in the row direction may be lower in height thanan upper edge of a wall of the first opening that faces the wall of thefirst opening that is adjacent to the second openings in the rowdirection, and an upper edge of a wall of the third opening that isadjacent to the second openings in the row direction may be lower inheight than an upper edge of a wall of the third opening that faces thewall of the third opening that is adjacent to the second openings in therow direction.

With this configuration, it is possible to maintain a high luminousefficiency and uniformize the film thickness of the light emittinglayers in each pixel to suppress luminance unevenness.

Also, in any of the above aspects, the wall of the first opening thatfaces the adjacent wall of the first opening may be smaller in gradientthan the wall of the first opening that is adjacent to the secondopenings, and the wall of the third opening that faces the adjacent wallof the third opening may be smaller in gradient than the wall of thethird opening that is adjacent to the second openings.

With this configuration, the height of bars, which hinder an ink flow inthe row direction, is low, and this facilitates the ink flow in the rowdirection. As a result, the ink spreads over the entire subpixel region900 a, and this uniformizes the film thickness of the light emittinglayers in each pixel to suppress luminance unevenness.

Also, in any of the above aspects, the first opening and the thirdopening may have a width in the row direction that increases upward, andthe second openings may have a width in the row direction and a width inthe column direction that increase upward.

With this configuration, it is possible to improve the light extractionefficiency and increase the viewing angle.

Also, in any of the above aspects, the organic EL display panel mayfurther comprise a bond layer that is provided above the counterelectrode layer and has a rear surface that is convex along the first,second, and third openings, and when refractive indices of the bondlayer and the insulating layer are represented by n₁ and n₂,respectively, the following relationships may be satisfied: 1.1≤n₁≤1.8(Formula 1); and |n₁−n₂|≥0.20 (Formula 2).

With this configuration, it is possible to improve the light extractionefficiency of the light emitting layers as the reflector by the openingsprovided in the insulating layer.

Also, in any of the above aspects, when depth, upper width in the rowdirection, and lower width in the row direction of the first, second,and third openings are represented by D, W_(h), and W₁, respectively,the following relationships may be satisfied: 0.5≤W₁/W_(h)≤0.8 (Formula3); and 0.5≤D/W₁≤2.0 (Formula 4).

With this configuration, the openings have trapezoidal cross sectionstaken along the row direction whose width increases upward, and thuslight emitting layers efficiently emit light upward.

Also, in any of the above aspects, in plan view, regions of thesubstrate where the first and second openings are provided may beluminous regions in the pixels, regions of the substrate that are eacharranged between two adjacent of the luminous regions in the columndirection may be non-luminous regions in the pixels, and the insulatinglayer may further have, in each of the non-luminous regions, a groovedportion with an upper opening and a bottom, the grooved portion beingcommunicated with the first openings in two pixels that are adjacent tothe non-luminous region in the column direction.

With this configuration, connection grooves included in the groovedportions increase the flow of the ink, which contains materials of thelight emitting layers, in the column direction, to suppress variation inapplication amount of the ink between the subpixels. This reducesvariation in film thickness of the light emitting layers to suppressluminance unevenness between the subpixels.

Also, in any of the above aspects, the organic functional layers may bein contact with the pixel electrode layers in the first, second, andthird openings, and may be separated from the pixel electrode layers inthe grooved portions.

With this configuration, the hole injection layers are exposed in theopenings so as to be in contact with the hole transport layer, and thisallows electrical charge supply in the openings from the hole injectionlayers to the hole transport layer. Thus, the openings correspond to theluminous regions. The hole injection layers are not exposed in bridginggrooves and connection grooves included in the grooved portions of theinsulating layer, which have groove-shaped cross sections and have upperopenings and bottoms. Accordingly, electrical charge supply from thehole injection layers to the hole transport layer is not performed inthe grooved portions. Thus, the grooved portions correspond to thenon-luminous regions.

DESCRIPTION OF EMBODIMENTS

1 Circuit Configuration

1.1 Circuit Configuration of Display Device 1

The following describes circuit configuration of an organic EL displaydevice 1 (hereinafter referred to just as display device 1) relating toan embodiment, with reference to FIG. 1.

As shown in FIG. 1, the display device 1 includes an organic EL displaypanel 10 (hereinafter referred to just as display panel 10) and a drivecontrol circuit unit 20 connected thereto.

The display panel 10 is an organic EL panel that makes use ofelectroluminescence of organic material, in which organic EL elementsare arranged in a matrix, for example. The drive control circuit unit 20includes four drive circuits 21-24 and a control circuit 25.

The arrangement of the circuits of the drive control circuit unit 20with respect to the display panel 10 in the display device 1 is notlimited to the configuration shown in FIG. 1.

1.2 Circuit Configuration of Display Panel 10

The display panel 10 includes a plurality organic EL elements that areunit pixels 100 e each of which are composed of three-color subpixels(not shown) emitting light of red (R), green (G), and blue (B) colors.Circuit configuration of the subpixels 100 se is described withreference to FIG. 2.

FIG. 2 is a schematic circuit diagram showing the circuit configurationof an organic EL element 100 corresponding to the subpixels 100 se ofthe display panel 10 used in the display device 1. The organic ELdisplay elements 100 constituting the unit pixels 100 e are arranged ina matrix as a display region of the display panel 10.

In the display panel 10 relating to the present embodiment, as shown inFIG. 2, each subpixel 100 se includes two transistors Tr₁ and Tr₂, asingle capacitance C, and an organic EL element unit EL as a lightemitting unit. The transistor Tr₁ is a drive transistor, and thetransistor Tr₂ is a switching transistor.

A gate G₂ and a source S₂ of the switching transistor Tr₂ arerespectively connected to a scanning line Vscn and a data line Vdat. Adrain D₂ of the switching transistor Tr₂ is connected to a gate G₁ ofthe drive transistor Tr₁.

A drain D₁ and a source S₁ of the drive transistor Tr₁ are respectivelyconnected to a power line Va and a pixel electrode layer (anode) of theorganic EL element unit EL. A counter electrode layer (cathode) of theorganic EL element unit EL is connected to a ground line Vcat.

Note that the capacitance C is provided so as to connect between thedrain D₂ of the switching transistor Tr₂ and the power line Va andconnect between the gate G₁ of the drive transistor Tr₁ and the powerline Va.

In the display panel 10, one unit pixel 100 e is composed of acombination of adjacent subpixels 100 se (for example, three subpixels100 se of R, G, and B luminescent colors), and a pixel region iscomposed of the subpixels 100 se that are distributed. A gate line GL isextracted from the gate G₂ of each subpixel 100 se, and is connected tothe scanning line Vscn that is connected to the outside of the displaypanel 10. Similarly, a source line SL is extracted from the source S₂ ofeach subpixel 100 se, and is connected to the data line Vdat that isconnected to the outside of the display panel 10.

Furthermore, the power line Va and the ground line Vcat of each subpixel100 se are collectively connected to the power line Va and the groundline Vcat.

2. Overall Configuration of Organic EL Display Panel 10

The following describes the display panel 10 relating to the presentembodiment with reference to the drawings. Note that the drawings arepattern diagrams and are not necessarily drawn to scale.

FIG. 3 is a schematic plan view showing part of the display panel 10relating to the present embodiment. FIG. 4A is an enlarged plan view ofa portion X1 in FIG. 3 indicating one pixel 100 of the display panel 10.FIG. 4B is an enlarged plan view of the portion X1 viewed from above aninsulating layer 122. FIG. 4C is a schematic cross-sectional view of anopening taken along a line B2-B2 in FIG. 4B. FIG. 5 is a perspectiveview from an oblique angle above a portion of the insulating layer 122corresponding to the subpixel of the organic EL element 100.

The display panel 10 is an organic EL display panel that makes use ofelectroluminescence of organic compound. In the display panel 10, theorganic EL elements 100 each constituting a pixel are arranged in amatrix on a substrate 100 x (thin film transistor (TFT) substrate) onwhich TFTs are formed. The display panel 10 is of the top-emission typeand emits light from an upper surface thereof. As shown in FIG. 3, thedisplay panel 10 includes the organic EL elements 100, constituting thepixels, arranged in a matrix. Here, the X-direction, the Y-direction,and the Z-direction in FIG. 3 are respectively referred to as the rowdirection, the column direction, and the thickness direction in thedisplay panel 10 in the present specification.

As shown in FIG. 3, the display panel 10 includes pixel electrode layers119 that are arranged on the substrate 100 x in a matrix, and includesan insulating layer 122 that covers the pixel electrode layers 119. Inthe case where the insulating layer 122 has an upper limit filmthickness of 10 μm or more, variation in film thickness at themanufacturing further increases, and control on the bottom linethickness is difficult. The insulating layer 122 should preferably havean upper limit film thickness of 7 μm or less in terms of productivitydecrease due to the increase in operation process. Also, the insulatinglayer 122 needs to have the film thickness and the bottom line thicknesssuch that as the film thickness decreases, a difference therebetweendecreases to substantially zero. For this reason, in the case where theinsulating layer 122 has a lower limit film thickness of 1 μm or less,it is difficult to obtain a desired bottom line thickness due toresolution requirements. The insulating layer 122 used in exposuremachines for typical flat display panels has a lower limit filmthickness of 2 μm. In view of the above, the insulating layer 122 shouldpreferably have a film thickness of 1 μm to 10 μm, and more preferably afilm thickness of 2 μm to 7 μm, for example. In the present embodiment,the insulating layer 122 has a film thickness of approximate 5.0 μm.

The pixel electrode layers 119 are rectangular in plan view, and aremade of a light-reflective material. The pixel electrode layers 119,which are arranged in a matrix, each correspond to any one of threesubpixels 100 aR, 100 aG, and 100 aB that are arranged in the rowdirection in the stated order (hereinafter referred to collectively assubpixels 100 a when no distinction is made therebetween).

The insulating layer 122 is layered above the pixel electrode layers 119which are arranged in a matrix. Above each of the pixel electrode layers119, the insulating layer 122 has at least one elongated first opening,and specifically two elongated first openings 122 z 1 and 122 z 2 in thepresent embodiment, and further has second openings 122 u. The firstopenings 122 z 1 and 122 z 2 are elongated in the column direction, andhereinafter referred to collectively as first openings 122 z when nodistinction is made therebetween. The second openings 122 u are shorterin the longitudinal direction than the first openings 122 z. The secondopenings 122 u are lined up adjacent to the first openings 122 z 1 and122 z 2. A range between the first opening 122 z 1 and the row of thesecond openings 122 u constitutes a bar 122 w 1, and a range between thefirst opening 122 z 2 and the row of the second openings 122 uconstitutes a bar 122 w 2.

Also, as shown in FIG. 4C, the openings 122 u functioning as thereflector each have a predetermined trapezoidal cross section takenalong a plane perpendicular to the longitudinal direction whose widthincreases upward. This configuration improves the light extractionefficiency of light emitting layers 123. Effective shape and refractiveindex conditions of the reflector will be described later.

A rectangular region surrounded by outer edges of the openings 122 z inthe row direction and column direction constitutes a luminous region 100a where light is emitted by organic compound. Here, among gaps betweenthe luminous regions 100 a, gaps in the row direction between theluminous regions 100 a arranged in the column direction are referred toas insulating sublayers 122X, and gaps in the column direction betweenthe luminous regions 100 a arranged in the row direction are referred toas insulating sublayers 122Y. Accordingly, outer edges of the luminousregions 100 a in the row direction are defined by outer edges of theinsulating sublayers 122X in the row direction, and outer edges of theluminous regions 100 a in the column direction are defined by outeredges of the insulating sublayers 122Y in the column direction.Hereinafter, outer edges in the row direction and outer edges in thecolumn direction are respectively referred to simply as row outer edgesand column outer edges.

The insulating sublayers 122X extending in the row direction (theX-direction in FIG. 3) are each arranged in the column direction abovethe column outer edges of two pixel electrode layers 119 that areadjacent in the column direction and above a region adjacent to thecolumn outer edges. A region where the insulating sublayer 122X isformed is a non-luminous region 100 b. As shown in FIG. 3, the displaypanel 10 includes the luminous regions 100 a and the non-luminousregions 100 b that alternate in the column direction. In each of thenon-luminous regions 100 b, a connection concave part 119 c (contacthole) connects the pixel electrode layer 119 and the source S₁ of theTFT via a connection electrode layer 117, and the pixel electrode layer119 has a contact region 119 b (contact window) for electricalconnection.

The display panel 10 includes banks that are arranged in lines. Columnbanks 522Y extending in the column direction (the Y-direction in FIG. 3)are arranged in the row direction above the insulating sublayers 122Y,such that each of the column banks 522Y is arranged above the row outeredges of two pixel electrode layers 119 that are adjacent in the rowdirection and above a region adjacent to the row outer edges.

Each two adjacent column banks 522Y have a gap 522 z therebetween, andaccordingly the display panel 10 includes a large number of alternatingcolumn banks 522Y and gaps 522 z.

The display panel 10 has three types of luminous regions 100 a, namelyluminous regions 100 aR, 100 aG, and 100 aB that respectively emit redlight, green light, and blue light (hereinafter referred to collectivelyas luminous regions 100 a when no distinction is made therebetween). Thegaps 522 z include red gaps 522 zR, green gaps 522 zG, and blue gaps 522zB that respectively correspond to the luminous regions 100 aR, 100 aG,and 100 aB (hereinafter referred to collectively as gaps 522 z when nodistinction is made therebetween). One set of the luminous regions 100aR, 100 aG, and 100 aB, which correspond to respective three subpixels100 se arranged in the row direction, constitutes a unit pixel 100 e forcolor display.

Column light shielding sublayers 129Y are provided above the pixelelectrode layers 119 so as to overlap row outer edges of the pixelelectrode layers 119. Also, row light shielding sublayers 129X areprovided above the pixel electrode layers 119 so as to overlap columnouter edges of the pixel electrode layers 119 and so as not to partiallyoverlap the contact regions 119 b.

3. Configuration of Components of Display Panel 10

The following describes the configuration of the organic EL elements 100of the display panel 10 with reference to schematic cross-sectionalviews in FIGS. 6 and 7. FIG. 6 is a schematic cross-sectional view takenalong a line A-A in FIG. 4B. FIG. 7 is a schematic cross-sectional viewtaken along a line B1-B1 in FIG. 4B.

The display panel 10 relating to the present embodiment is of an organicEL display panel of the top-emission type, and includes the substrate100 x (TFT substrate) on which the TFTs are formed in a lower part inthe Z-axis direction and the organic EL element units are formedthereon.

3.1 Substrate 100 x (TFT Substrate)

As shown in FIG. 6, gate electrodes 101 and 102 are formed with aninterval therebetween on a lower substrate 100 p, and a gate insulatinglayer 103 is formed so as to cover respective surfaces of the gateelectrodes 101 and 102 and the lower substrate 100 p. Channel layers 104and 105 are formed on the gate insulating layer 103 so as torespectively correspond to the gate electrodes 101 and 102. A channelprotection layer 106 is formed so as to cover respective surfaces of thechannel layers 104 and 105 and the gate insulating layer 103.

Source electrodes 107 and drain electrodes 108 are formed with aninterval therebetween on the channel protection layer 106 so as tocorrespond to the gate electrodes 101 and the channel layers 104.Similarly, source electrodes 110 and drain electrodes 109 are formedwith an interval therebetween on the channel protection layer 106 so asto correspond to the gate electrode 102 and the channel layer 105.

Source lower electrodes 111 and 115 are respectively formed below thesource electrodes 107 and 110 by being inserted through the channelprotection layer 106. Drain lower electrodes 112 and 114 arerespectively formed below the drain electrodes 108 and 109 by beinginserted through the channel protection layer 106. The source lowerelectrodes 111 and the drain lower electrodes 112 have low portions inthe Z-axis direction that are in contact with the channel layer 104. Thedrain lower electrodes 114 and the source lower electrodes 115 have lowportions in the Z-axis direction that are in contact with the channellayer 105.

Also, the drain electrodes 108 are connected with the gate electrodes102 via contact plugs 113 that are provided by being inserted throughthe gate insulating layer 103 and the channel protection layer 106.

Note that the gate electrodes 101, the source electrodes 107, and thedrain electrodes 108 respectively correspond to the gate G₂, the sourceS₂, and the drain D₂ in FIG. 2. Similarly, the gate electrodes 102, thesource electrodes 110, and the drain electrodes 109 respectivelycorrespond to the gate G₁, the source S₁, and the drain D₁ in FIG. 2.Accordingly, the switching transistor Tr₂ and the drive transistor Tr₁are respectively formed leftward and rightward in the Y-axis directionin FIG. 6.

Note that the above configuration is just an example, and thearrangement of the transistors Tr₁ and Tr₂ is not limited to that inFIG. 6 and any configuration may be employed such as top-gate,bottom-gate, channel-etch, and etch-stop.

Passivation layers 116 are formed so as to cover the respective surfacesof the source electrodes 107 and 110, the drain electrodes 108 and 109,and the channel protection layer 106. The passivation layers 116 havecontact holes 116 a above part of upper portions of the sourceelectrodes 110. The connection electrode layers 117 are layered so as tobe along side walls of the contact holes 116 a.

The connection electrode layers 117 have lower portions in the Z-axisdirection that are connected with the source electrodes 110, and alsohave upper portions that are partially on the passivation layers 116. Aninterlayer insulating layer 118 is layered so as to cover respectivesurfaces of the connection electrode layers 117 and the passivationlayers 116.

3.2 Organic EL Element Unit

(1) Pixel Electrode Layers 119

The pixel electrode layers 119 are formed in units of subpixels on theinterlayer insulating layer 118. The pixel electrode layers 119 areprovided for supplying carries to the light emitting layers 123. Whenfunctioning as anodes for example, the pixel electrode layers 119 supplyholes to the light emitting layers 123. Also, since the display panel 10is of the top-emission type, the pixel electrode layers 119 arelight-reflective. The pixel electrode layers 119 are rectangular andplate-like. The pixel electrode layers 119 are arranged on the substrate100 x with intervals 6X therebetween in the row direction and withintervals δY therebetween in the column direction in the gaps 522 z.Furthermore, the pixel electrode layers 119 have the connection concaveparts 119 c that are connected with the connection electrode layers 117through contact holes 118 a that are provided above the connectionelectrode layers 117 in the inter insulating layer 118. Accordingly, thepixel electrode layers 119 are each connected with the source S₁ of theTFT via the connection electrode layer 117. The connection concave parts119 c of the electrode layers 119 are concave toward the substrate 100x.

The pixel electrode layers 119 have column outer edges 119 a 1 and 119 a2, and the connection concave parts 119 c are provided on the side ofthe column outer edges 119 a 2. The contact regions 119 b are rangesfrom the column outer edges 119 a 2 to regions including the connectionconcave parts 119 c.

(2) Hole Injection Layers 120

Hole injection layers 120 are layered on the pixel electrode layers 119so as to be in contact with the pixel electrode layers 119. The holeinjection layers 120 have a function of transporting holes, which areinjected from the pixel electrode layers 119, to the light emittinglayers 123.

(3) Insulating Layer 122

The insulating layer 122 is made of an insulating material, and isformed so as to cover at least end edges of the pixel electrode layers119 which are arranged in a matrix.

Above each of the pixel electrode layers 119 except the contact regions119 b, the insulating layer 122 has the two first openings 122 z 1 and122 z 2 and the plurality of second openings 122 u. The first openings122 z 1 and 122 z 2 are elongated in the column direction. The secondopenings 122 u are shorter in longitudinal length than the firstopenings 122 z, and are lined up adjacent to the first openings 122 z 1and 122 z 2. As shown in FIGS. 6 and 7, the insulating layer 122 has thefirst openings 122 z and the second openings 122 u above the pixelelectrode layers 119. The hole injection layers 120, which are layeredon the pixel electrode layers 119, are exposed in these openings so asto be in contact with hole transport layers 121 which are describedlater. This configuration allows electrical charge supply in theseopenings from the pixel electrode layers 119 to the hole transportlayers 121. Accordingly, the minimum rectangular region including thefirst openings 122 z and the second openings 122 u is the luminousregion 100 a where light is emitted by organic compound of any of the R,G, and B colors. Also, a gap of the insulating layer 122 between eachtwo luminous regions 100 a which are arranged in the column direction isthe non-luminous region 100 b. The insulating layer 122 has the bar 122w 1, which is provided between each pair of the first opening 122 z 1and the row of the second openings 122 u, and has the bar 122 w 2, whichis provided between each pair of the first opening 122 z 2 and the rowof the second openings 122 u.

Also, the insulating layer 122 includes the insulating sublayers 122Y,which are gaps between luminous regions 100 a extending in the columndirection and arranged in the row direction. Accordingly, the insulatingsublayers 122Y define the row outer edges of the luminous regions 100 ain the subpixels 100 se. The insulating sublayers 122Y and the bars 122w 1 and 122 w 2 each have a trapezoidal cross section taken along therow direction whose width decreases upward.

Here, upper edges 122 wb of walls of the second openings 122 u that arefurther from the row outer edges of the subpixels 100 se are lower inheight than upper edges 122Yb of walls of the first openings 122 z thatare nearest the row outer edges of the subpixels 100 se. In other words,the upper edges 122 wb of the bars 122 w 1 and 122 w 2 are lower inheight than the upper edges 122Yb of the insulating sublayers 122Y. Thisconfiguration increases the flow of an ink, which contains organiccompound as materials of the light emitting layers 123, in each subpixelduring a manufacturing process. As a result, it is possible to suppressan insufficient spread of the ink containing the materials of the lightemitting layers 123 in the subpixel, and suppress variation inapplication amount of the ink in the subpixel.

Furthermore, a gradient φ of the walls of the second openings 122 u thatare further from the row outer edges of the subpixels 100 se is largerthan a gradient θ of the walls of the first openings 122 z that arenearest the row outer edges of the subpixels 100 se. This configurationimproves the light extraction efficiency in parts of the first openings122 z that are further from the row outer edges of the subpixels 100 se,and also increases the viewing angle in parts of the first openings 122z that are nearest the row outer edges of the subpixels 100 se, therebyto cause the light emitting layers 123 to efficiently emit light upward.

Also, the insulating layer 122 includes the insulating sublayers 122X(corresponding to the non-luminous regions 100 b), which are gapsbetween luminous regions 100 a extending in the row direction andarranged in the column direction. As shown in FIG. 4A, the insulatingsublayers 122X are arranged above the contact regions 119 b of the pixelelectrode layers 119 and above the column outer edges 119 a 1 and 119 a2 of the pixel electrode layers 119 which are adjacent to each other inthe column direction. The insulating sublayers 122X cover the columnouter edges 119 a 1 and 119 a 2 of the pixel electrode layers 119thereby to prevent electric leakage between the pixel electrode layers119 and the counter electrode layer 125, and thereby to define thecolumn outer edges of the luminous regions 100 a in the subpixels 100se.

Although not illustrated, the insulating sublayers 122X each haverespective connection grooves that are communicated with the openings122 z 1 and 122 z 2 provided above the substrate 100 x. The connectiongrooves have upper openings and bottoms. The connection grooves may becommunicated with the openings 122 z 1 and 122 z 2 provided in subpixelsadjacent in the column direction. With this configuration, theconnection grooves increase the flow of the ink, which contains organiccompound as materials of the light emitting layers 123, in the columndirection, thereby to suppress variation in application amount of theink between the subpixels. Also, the hole injection layers 120 are notexposed in the connection grooves of the insulating layer, which have agroove-shape cross section and have upper openings and bottoms.Accordingly, the connection grooves do not contribute to light emission.The connection grooves have trapezoidal cross sections taken along aplane perpendicular to the longitudinal direction whose width increasesupward.

The insulating sublayers 122X with an upper limit film thickness ofgreater than 2 μm deteriorate the ink spread. Meanwhile, the insulatingsublayers 122X with an upper limit film thickness of 1.2 μm or smallerfurther improve the ink spread. Also, the insulating sublayers 122X witha lower limit film thickness of 0.1 μm or greater cover end parts of thepixel electrode layers 119 thereby to achieve manufacturing at aconstant yield with no short between the pixel electrode layers 119 anda counter electrode layer 125. The insulating sublayers 122X with alower limit film thickness of 0.2 μm or greater reduce the above shortfailure caused by variation in film thickness thereby to achieve stablemanufacturing. In the case where the insulating sublayers 122X have theconnection grooves, the same applies to the film thickness of theinsulating sublayers 122X in the bottoms of the connection grooves.

Accordingly, the film thickness of the insulating sublayers 122X in theconnection grooves and the film thickness of the insulating sublayers122X in the bottoms of the connection grooves, if provided, each shouldpreferably be 0.1 μm to 2 μm, and more preferably 0.2 μm to 1.2 μm, forexample. In the present embodiment, these film thicknesses are eachapproximate 1.0 μm.

(4) Column Banks 522Y

The column banks 522Y, extending in the column direction, are arrangedin the row direction above the insulating sublayers 122Y. The columnbanks 522Y define the row outer edges of the light emitting layers 123,which are formed by stemming the flow in the row direction of the inkcontaining organic compound as the material of the light emitting layers123. The column banks 522Y are each provided above a pair of the rowouter edges 119 a 3 and 119 a 4 of two adjacent pixel electrode layers119 so as to partially overlap the pixel electrode layers 119. Thecolumn banks 522Y are linear and each have a trapezoidal cross sectiontaken along the row direction whose width decreases upwards. The columnbanks 522Y are provided in the column direction so as to beperpendicular to the insulating sublayers 122X, and have upper surfacesthat are higher in position than the upper surfaces 122 xb of theinsulating sublayers 122X.

(5) Hole Transport Layers 121

Hole transport layers 121 are layered on the insulating layer 122 and onthe hole injection layers 120 in the openings 122 z, and is in contactwith the hole injection layers 120 in bottoms of the openings 122 z. Thehole transport layers 121 have a function of transporting holes, whichare injected from the hole injection layers 120, to the light emittinglayers 123.

(6) Light Emitting Layers 123

The display panel 10 includes a large number of alternating column banks522Y and gaps 522 z. The light emitting layers 123 extend in the columndirection on the upper surfaces of the hole transport layers 121 in thegaps 522 z which are defined by the column banks 522Y. The lightemitting layer 123 emitting light of the R, G, and B colors are formedrespectively in the red gaps 522 zR, the green gaps 522 zG, and the bluegaps 522 zB, which respectively correspond to the luminous regions 100aR, 100 aG, and 100 aB.

The light emitting layers 123 are made of organic compound, and have afunction of emitting light through recombination of holes and electronsthereinside. In the gaps 522 z, the light emitting layers 123 areprovided so as to be linear and extend in the column direction.

Light is emitted from only parts of the light emitting layers 123 towhich carriers are supplied from the pixel electrode layers 119, andaccordingly no electroluminescence of organic compound occurs in regionsof the light emitting layers 123 where the insulating layer 122 isprovided, which is made of an insulating material. Thus, light isemitted from only parts of the light emitting layers 123, positioned inthe first openings 122 z and the second openings 122 u, where noinsulating layer 122 is provided. These minimum rectangular regionsincluding the first openings 122 z and the second openings 122 u are theluminous regions 100 a.

In the light emitting layers 123, light is not emitted from parts thatare located above the insulating sublayers 122X. These parts are thenon-luminous regions 100 b. In other words, the non-luminous regions 100b correspond to the insulating sublayers 122X that are projected in planview.

(7) Electron Transport Layer 124

An electron transport layer 124 is formed on the column banks 522Y andon the light emitting layers 123 in the gaps 522 z which are defined bythe column banks 522Y. In this example, the electron transport layer 124extends over parts of the column banks 522Y that are exposed from thelight emitting layers 123. The electron transport layer 124 has afunction of transporting electrons, which are injected from the counterelectrode layer 125, to the light emitting layers 123.

(8) Counter Electrode Layer 125

The counter electrode layer 125 is formed so as to cover the electrontransport layer 124. The counter electrode layer 125 is continuous overthe entire display panel 10, and may be connected to a bus-bar wiringper pixel or per several pixels (not shown). The counter electrode layer125 and the pixel electrode layers 119 in pairs sandwich the lightemitting layers 123 therebetween to form an energizing path to supplycarries to the light emitting layers 123. When functioning as a cathodefor example, the counter electrode layer 125 supplies electrons to thelight emitting layers 123. The counter electrode layer 125 is formed soas to be along a surface of the electron transport layer 124, and is acommon electrode for the light emitting layers 123.

Since the display panel 10 is of the top-emission type, the counterelectrode layer 125 is made of a light-transmissive and conductivematerial. The counter electrode layer 125 is made for example of indiumtin oxide (ITO) or indium zinc oxide (IZO). Alternatively, the counterelectrode layer 125 may be a thin electrode film made of silver (Ag),aluminum (Al), or the like.

(9) Sealing Layer 126

A sealing layer 126 is formed so as to cover the counter electrode layer125. The sealing layer 126 is provided in order to suppress degradationof the light emitting layers 123 due to exposure to moisture, air, andso on. The sealing layer 126 is provided for the entire display panel 10so as to cover an upper surface of the counter electrode layer 125.Since the display panel 10 is of the top-emission type, the sealinglayer 126 is made of a light-transmissive material such as siliconnitride and silicon oxynitride.

(10) Bond Layer 127

A bond layer 127 bonds the sealing layer 126 and a CF substrate 131 thatis provided above the sealing layer 126 in the Z-axis direction. The CFsubstrate 131 includes an upper substrate 130 that has a lower mainsurface in the Z-axis direction on which color filter layers 128 and alight shielding layer 129 are formed. The bond layer 127 bonds a rearpanel that is composed of the substrate 100X and the layers ranging fromthe pixel electrode layers 119 to the sealing layer 126, to the CFsubstrate 131. The bond layer 127 also has a function of preventing thelayers from being exposed to moisture, air, and so on.

(11) Upper Substrate 130

The CF substrate 131, which includes the upper substrate 130 on whichthe color filter layers 128 and the light shielding layer 129 areformed, is bonded onto the bond layer 127. Since the display panel 10 isof the top-emission type, the upper substrate 130 is made of alight-transmissive material such as a cover glass and a transparentresin film. Also, providing the upper substrate 130 for example improvesthe rigidity of the display panel 10, and prevents moisture, air, and soon from intruding the display panel 10.

(12) Color Filter Layers 128

The color filter layers 128 are formed on the upper substrate 130 so asto correspond in position and color to the luminous regions 100 a. Thecolor filter layers 128 are transparent layers that are provided fortransmitting visible light of wavelength corresponding to the R, G, andB colors, and have a function of transmitting light emitted from the R,G, and B pixels and correcting chromaticity of the light. In thisexample, the red color filter layers 128R, the green color filter layers128G, and the blue color filter layers 128B are respectively formedabove the luminous regions 100 aR in the red gaps 522 zR, the luminousregions 100 aG in the green gaps 522 zG, and the luminous regions 100 aBin the blue gaps 522 zB.

(13) Light Shielding Layer 129

The light shielding layer 129 is formed on the upper substrate 130 so asto correspond in position to boundaries between the luminous regions 100a in the pixels.

The light shielding layer 129 is a black resin layer that is provided inorder to prevent transmission of visible light of wavelengthcorresponding to the R, G, and B colors. The light shielding layer 129is made for example of a resin material including black pigment havingexcellent light absorbing property and light shielding property. Thelight shielding layer 129 includes the column light shielding sublayers129Y, which extend in the column direction and are arranged in the rowdirection, and the row light shielding sublayers 129X, which extend inthe row direction and are arranged in the column direction. A latticeshape is formed by the column light shielding sublayers 129Y and the rowlight shielding sublayers 129X. In the organic EL elements 100, thecolumn light shielding sublayers 129Y are arranged so as to overlap theinsulating sublayers 122Y as shown in FIG. 7, and the row lightshielding sublayers 129X are arranged so as to overlap the insulatingsublayers 122X as shown in FIG. 6.

3.3 Materials of Components

The following describes an example of materials of the components.

(1) Substrate 100 x (TFT Substrate)

The substrate 100 x is made of a known material for TFT substrate.

The lower substrate 100 p is for example a glass substrate, a quartzsubstrate, a silicon substrate, a metal substrate made of molybdenumsulfide, copper, zinc, aluminum, stainless, magnesium, iron, nickel,gold, or silver, a semiconductor substrate made of gallium arsenide baseor the like, or a plastic substrate.

Either thermoplastic resin or thermosetting resin may be used as aplastic material. The plastic material may be for example a single layerof any one type of the following materials or a laminate of any two ormore types of the following materials including polyethylene,polypropylene, polyamide, polyimide (PI), polycarbonate, acrylic resin,polyethylene terephthalate (PET), polybutylene terephthalate,polyacetal, other fluororesin, thermoplastic elastomer such as styreneelastomer, polyolefin elastomer, polyvinyl chloride elastomer,polyurethane elastomer, fluorine rubber elastomer, and chlorinatedpolyethylene elastomer, epoxy resin, unsaturated polyester resin,silicone resin, polyurethane, or copolymer, blend, polymer alloy or thelike mainly including such a material.

The gate electrodes 101 and 102 are made for example of a laminate ofcopper (Cu) and molybdenum (Mo). Alternatively, other metal material isadoptable.

The gate insulating layer 103 is made for example of any knownelectrically-insulating material such as silicon dioxide (SiO₂) andsilicon nitride (SiNx), regardless of whether the material is organic orinorganic.

The channel layers 104 and 105 are made of oxide semiconductor includingat least one of indium (In), gallium (Ga), and zinc (Zn).

The channel protection layer 106 is made for example of siliconoxynitride (SiON), silicon nitride (SiN), or aluminum oxide (AlOx).

The source electrodes 107 and 110 and the drain electrodes 108 and 109are made for example of a laminate of copper-manganese (CuMn), copper(Cu), and molybdenum (Mo).

The similar material is adoptable for the source lower electrodes 111and 115 and the drain lower electrodes 112 and 114.

The passivation layers 116 are made for example of silicon dioxide(SiO₂), a combination of silicon nitride (SiN) and silicon oxynitride(SiON), or a combination of silicon oxide (SiO) and silicon oxynitride(SiON).

The connection electrode layers 117 are made for example of a laminateof copper-manganese (CuMn), copper (Cu), and molybdenum (Mo).Alternatively, the material of the connection electrode layers 117 maybe appropriately selected from conductive materials.

The interlayer insulating layer 118 is made for example of an organiccompound such as polyimide, polyamide, and acrylic resin, and has a filmthickness of 2000 nm to 8000 nm for example.

(2) Pixel Electrode Layers 119

The pixel electrode layers 119 are made of a metal material. The displaypanel 10 relating to the present embodiment, which is of thetop-emission type, should preferably have a surface part that is highlylight-reflective. In the display panel 10 relating to the presentembodiment, the pixel electrode layers 119 each may be a laminateincluding layers selected from a metal layer, an alloy layer, and atransparent conductive layer. The metal layer is made for example of ametal material including silver (Ag) or aluminum (Al). The alloy layeris made for example of alloy of silver, palladium, and copper (APC),alloy of silver, rubidium, and gold (ARA), alloy of molybdenum andchromium (MoCr), or alloy of nickel and chromium (NiCr). The transparentconductive layer is made for example of indium tin oxide (ITO) or indiumzinc oxide (IZO).

(3) Insulating Layer 122

The insulating layer 122 is made of an insulating material. The organicmaterial of the insulating layer 122 is for example an organicphotosensitive resin material such as acrylic resin, polyimide resin,and novolac phenolic resin. Acrylic resin should preferably be usedbecause of having a low refractive index and thus being desirable as areflector. Alternatively, in the case where the insulating layer 122 ismade of an inorganic material, silicon oxide (SiO) for example shouldpreferably be used in terms of refractive index. The inorganic materialmay be for example silicon nitride (SiN) or silicon oxynitride (SiON).The insulating layer 122 has a film thickness of approximate 5 μm. Thefilm thickness of the insulating layer 122 is not limited to this, andalternatively may fall within a range of for example 0.1 μm to 10 μm.

(4) Column Banks 522Y

The column banks 522Y are made of an insulating organic material such asresin. Examples of the organic material of the column banks 522Y includeacrylic resin, polyimide resin, and novolac phenolic resin. The columnbanks 522Y should preferably have an organic solvent resistance. Also,the column banks 522Y sometimes undergo an etching process, a bakingprocess, and so on during the manufacturing process, and accordinglyshould preferably be made of a highly resistant material in order toavoid excessive distortion, transformation, and the like due to suchprocesses. Also, fluorine processing may be performed on surfaces of thecolumn banks 522Y in order to provide the surfaces with waterrepellency. Alternatively, the column banks 522Y may be made of amaterial containing fluorine.

(5) Hole Injection Layers 120

The hole injection layers 120 are made for example of oxide of a metalsuch as silver (Ag), molybdenum (Mo), chromium (Cr), vanadium (V),tungsten (W), nickel (Ni), and iridium (Ir), or a conductive polymermaterial such as polyethylenedioxythiophene (PEDOT).

In the case where the hole injection layers 120 are made of oxide oftransition metal, the hole injection layers 120 have energy levelsbecause oxide of transition metal has oxidation numbers. Thisfacilitates hole injection, and thus reduces driving voltage.

(6) Hole Transport Layers 121

The hole transport layers 121 are made for example of a high-molecularcompound such as polyfluorene, polyfluorene derivative, polyallylamine,and polyallylamine derivative.

(7) Light Emitting Layers 123

The light emitting layers 123 have a function of emitting light byexcitation resulting from injection and recombination of holes andelectrons, as described above. The light emitting layers 123 need to bemade of a luminous organic material by a wet printing method.

Specifically, the light emitting layers 123 should preferably be madefor example of a fluorescent substance disclosed in Japanese PatentApplication Publication No. H05-163488, such as oxinoid compound,perylene compound, coumarin compound, azacoumarin compound, oxazolecompound, oxadiazole compound, perinone compound, pyrrolopyrrolecompound, naphthalene compound, anthracene compound, fluorene compound,fluoranthene compound, tetracene compound, pyrene compound, coronenecompound, quinolone compound and azaquinolone compound, pyrazolinederivative and pyrazolone derivative, rhodamine compound, chrysenecompound, phenanthrene compound, cyclopentadiene compound, stilbenecompound, diphenylquinone compound, styryl compound, butadiene compound,dicyanomethylenepyran compound, dicyanomethylenethiopyran compound,fluorescein compound, pyrylium compound, thiapyrylium compound,selenapyrylium compound, telluropyrylium compound, aromatic aldadienecompound, oligophenylene compound, thioxanthene compound, anthracenecompound, cyanine compound, acridine compound, and metal complex of8-hydroxyquinoline compound, metal complex of 2-bipyridine compound,complex of a Schiff base and group III metal, oxine metal complex, andrare earth complex.

(8) Electron Transport Layer 124

The electron transport layer 124 is made for example of oxydiazolederivative (OXD), triazole derivative (TAZ), or phenanthrolinederivative (BCP Bphen).

(9) Counter Electrode Layer 125

The counter electrode layer 125 is made for example of indium tin oxide(ITO) or indium zinc oxide (IZO). Alternatively, the counter electrodelayer 125 may be a thin electrode film made of silver (Ag), aluminum(Al), or the like.

(10) Sealing Layer 126

The sealing layer 126 has a function of preventing the organic layerssuch as the light emitting layers 123 from being exposed to moisture,air, and so on. The sealing layer 126 is made for example of alight-transmissive material such as silicon nitride (SiN) and siliconoxynitride (SiON). Also, a resin sealing layer that is made of a resinmaterial such as acrylic resin and silicone resin may be provided on alayer that is made of a material such as silicon nitride (SiN) andsilicon oxynitride (SiON).

Since the display panel 10 relating to the present embodiment is of thetop-emission type, the sealing layer 126 needs to be made of alight-transmissive material.

(11) Bond Layer 127

The bond layer 127 is made for example of a resin adhesive. Alight-transmissive resin material is adoptable such as acrylic resin,silicone resin, and epoxy resin.

(12) Upper Substrate 130

The upper substrate 130 is made for example of a light-transmissivematerial such as glass, quartz, and plastic.

(13) Color Filter Layers 128

The color filter layers 128 are made of a known resin material (forexample, the color resist manufactured by JSR Corporation) or the like.

(14) Light Shielding Layer 129

The light shielding layer 129 is made mainly of an ultraviolet curableresin, such as an ultraviolet curable acrylic resin, to which blackpigment is added. The black pigment is for example carbon black pigment,titanium black pigment, metal oxide pigment, or organic pigment.

3.4 Improvement of Light Extraction Efficiency by Reflector

The display panel 10 includes: the reflector (reflective structure) thatis constituted from the insulating layer 122, which has the firstopenings 122 z and the second openings 122 u, and the bond layer 127,which has a rear surface that is convex along the first openings 122 zand the second openings 122 u of the insulating layer 122; and the lightemitting layers 123, which are provided between the insulating layer 122and the bond layer 127. The first openings 122 z and the second openings122 u each have a profile of a trapezoidal cross section taken along therow direction whose width increases upward. When the refractive indicesof the bond layer 127 and the insulating layer 122 are represented by n₁and n₂, respectively, the following relationships are satisfied.

1.1≤n ₁≤1.8  (Formula 1)

|n ₁ −n ₂|≥0.20  (Formula 2)

Here, the refractive index n₂ should preferably be 1.4 to 1.6.

Also, when a depth, an upper width, and a lower width in the crosssection of the first openings 122 z and the second openings 122 u arerepresented by D, W_(h), and W₁, respectively, the followingrelationships should preferably be satisfied.

0.5≤W ₁ /W _(h)≤0.8  (Formula 3)

0.5≤D/W ₁≤2.0  (Formula 4)

With the above shape and refractive index conditions, it is possible toimprove the light extraction efficiency of the light emitting layers 123owing to the first openings 122 z and the second openings 122 u of theinsulating layer 122, which function as the reflector. According to theinventors' consideration, this results in increase of luminance persubpixel by 1.2 times to 1.5 times of that in display panels with noreflector.

4. Manufacturing Method of Display Panel 10

The following describes a manufacturing method of the display panel 10with reference to the drawings. FIGS. 8A to 8E, FIGS. 9A to 9C, andFIGS. 10A to 10C are schematic cross-sectional views showing theprocesses of manufacturing the display panel 10, taken along a line atthe same position as the line A1-A1 in FIG. 4B. FIGS. 12A to 12D andFIGS. 13A to 13D are schematic cross-sectional views showing theprocesses of manufacturing the display panel 10, taken along a line atthe same position as the line B1-B1 in FIG. 4B.

(1) Formation of Substrate 100 x (TFT Substrate)

First, a substrate 100 x 0 is prepared. The substrate 100 x 0 has formedthereon components from drain electrodes 101 and 102 to sourceelectrodes 107 and 110 and drain electrodes 108 and 109. The substrate100 x 0 is manufactured by a known TFT manufacturing method (FIG. 8A).

Next, passivation layers 116 are formed for example with a plasma CVDmethod or a sputtering method so as to cover the source electrodes 107and 110, the drain electrodes 108 and 109, and a channel protectionlayer 106 (FIG. 8B).

Next, a contact hole 116 a is provided in each of the source electrodes110 in the passivation layers 116 with a dry etching method (FIG. 8C).The contact hole 116 a is provided so as to have a bottom in which asurface of the source electrode 110 is exposed.

Next, connection electrode layers 117 are formed so as to be along innerwalls of the contact holes 116 a provided in the passivation layers 116.The connection electrode layers 117 have upper portions that arepartially on the passivation layers 116. The connection electrode layers117 are formed by forming a metal film with for example the sputteringmethod, and then patterning the metal film with a photolithographymethod and a wet etching method. Furthermore, an interlayer insulatinglayer 118 is formed by applying an organic material onto the connectionelectrode layers 117 and the passivation layers 116 so as to cover theselayers and planarizing a surface of the applied organic material (FIG.8D).

(2) Formation of Pixel Electrode Layers 119

Contact holes are provided above the connection electrode layers 117 inthe interlayer insulating layer 118. Then, pixel electrode layers 119and hole injection layers 120 are formed in the stated order in thecontact holes (FIG. 8E). The pixel electrode layers 119 and the holeinjection layers 120 are respectively formed by forming a metal film anda metal oxide film with the sputtering method, a vacuum depositionmethod, or the like, and then patterning the metal film and the metaloxide film with the photolithography method. Note that the pixelelectrode layers 119 are electrically connected with the connectionelectrode layers 117.

(3) Formation of Insulating Layer 122

In a formation process of an insulating layer 122, a reflector iscomplete through application of an organic material onto the substrate,exposure, development, and firing (for approximate 60 minutes atapproximate 230° C.). In the exposure, a photomask PM is used as ahalftone mask, which varies transmissivity so as correspond to anexposure amount suitable for each film thickness. Specific descriptionis given below. First, a photosensitive resin film 122R is formed usingan organic photosensitive resin material such as acrylic resin,polyimide resin, and novolac phenolic resin (FIGS. 9A and 12A). Then,the photosensitive resin film 122R is dried and a solvent thereof isvaporized to a certain degree. Then, a photomask PM having predeterminedopenings is overlaid above the photosensitive resin film 122R.Ultraviolet irradiation is performed on the photomask PM thereby toexpose a photoresist made of photosensitive resin or the like totransfer patterns of the photomask PM to the photoresist (FIGS. 9B and12B). In the present embodiment, the photomask PM is for example ahalftone mask for positive photoresists that includes transmissive parts(vertical stripe portions in the figures) corresponding to openings 122z and semi-transmissive parts (lattice portions in the figures)corresponding to bars 122 w 1 and 122 w 2. The transmissive parts areparts through which light transmits. The semi-transmissive parts areintermediate between the transmissive parts and light shielding parts interms of transmissivity. As a result of the exposure, the photoresisthas opening patterns corresponding in shape to the transmissive parts,which correspond to the openings 122 z, and has groove patterns havingan intermediate exposure amount and corresponding in shape to thesemi-transmissive parts, which correspond to the bars 122 w 1 and 122 w2. With use of the halftone mask, it is possible to form patterns havingdifferent exposure amounts in a photoresist by a single exposure.

Next, development is performed on the photoresist on which patterns ofinsulating sublayers 122X and 122Y, first openings 122 z, and secondopenings 122 u are formed. As a result, an insulating layer 122 iscomplete (FIGS. 9C and 12B). Parts of the photoresist, which have theopening patterns with the highest exposure amount, are developed andremoved, and thus result in no insulating layer 122. Parts of thephotoresist, which have the grooves patterns with the intermediateexposure amount, are developed, and thus result in the insulating layer122 having a film thickness of approximate 3 μm. Pattern parts of thephotoresist, which are not exposed, result in the insulating layer 122having a film thickness of approximate 5 μm.

At this time, the first opening 122 z and the second openings 122 u eachhave a trapezoidal cross section taken along a plane perpendicular tothe longitudinal direction whose width increases upward, as describedabove. This allows to form the insulating layer 122 including theinsulating sublayers 122X and 122Y of a thickness of approximate 5 μmthat surround regions defining pixels. Also, the patterning is performedsuch that surfaces of the hole injection layers 120 are exposed in thebottoms of the first openings 122 z 1 and 122 z 2 and the secondopenings 122 u and such that parts of the insulating layer 122, whichcorrespond to upper edges 122 wb of the bars 122 w 1 and 122 w 2, have afilm thickness of approximate 3 μm.

The insulating layer 122 may be manufactured so as to have the partswith a thickness of approximate 3 μm corresponding to the upper edges122 wb of the bars 122 w 1 and 122 w 2 by using a general mask patternfor the parts corresponding to the bars 122 w 1 and 122 w 2 instead ofthe halftone mask, and performing exposure for an increased period anddevelopment.

(4) Formation of Column Banks 522Y

Column banks 522Y are formed as follows. First, a film 522YR made of amaterial of the column banks 522Y such as a photosensitive resinmaterial is formed on the insulating layer 122 with a spin coat methodor the like (FIG. 12C). Then, the film 522YR is patterned to such thatgaps 522 z are provided. As a result, the column banks 522Y are formed(FIG. 12D). The gaps 522 z are provided by performing exposure through amask overlaid above the film 522YR and then performing development. Thecolumn banks 522Y, extending in the column direction along uppersurfaces of the insulating sublayers 122Y, are arranged with the gaps522 z therebetween in the row direction.

(5) Formation of Hole Transport Layers 121

Hole transport layers 121 are formed on the hole injection layers 120and the insulating layer 122 (FIGS. 10A and 13A). The hole transportlayers 121 are formed by applying an ink containing a material of thehole transport layers 121 onto the inside of the gaps 522 z, which aredefined by the column banks 522Y, with the ink jet method, and thenfiring the ink. Alternatively, the hole transport layers 121 are formedby depositing metal oxide films such as tungsten oxide films with thesputtering method. Note that, after the deposition, the films may bepatterned in units of pixels with the photolithography method and anetching method.

(6) Formation of Light Emitting Layers 123

In the gaps 522 z which are defined by the column banks 522Y, lightemitting layers 123 and an electron transport layer 124 are formed onthe hole transport layers 121 in the stated order.

The light emitting layers 123 are formed by applying an ink containing amaterial of the light emitting layers 123 onto the inside of the gaps522 z, which are defined by the column banks 522Y, with the ink jetmethod, and then firing the ink.

In formation of the light emitting layers 123, a solution for formingthe light emitting layers 123 is first applied with use of an inkdischarge device. Specifically, light emitting layers of the R, G, and Bcolors alternate above the substrate 100 x in line in the stated orderin the lateral direction in the figures. In this process, the gaps 522z, which are regions where subpixels are to be formed, are each filledusing the ink jet method with any of inks 123RI, 123GI, and 123BIrespectively containing materials of organic light emitting layers ofthe R, G, and B colors (FIG. 13B). Then, the inks are dried under areduced pressure and are baked. As a result, the light emitting layers123R, 123G, and 123B are complete (FIGS. 10B and 13C).

(Method of Applying Solution for Light Emitting Layer Formation)

The following describes a process of forming the light emitting layers123 with the ink jet method for mass production. FIG. 15 is a schematicview showing a process of applying inks for light emitting layerformation to regions of a lattice shape above the substrate that aredefined by the insulating sublayers 122X and 122Y.

In formation of the light emitting layers 123, light emitting layers ofthe R, G, and B colors are formed in the regions defined by the banksarranged in lines, with use of three color inks, namely, the red ink123RI, the green ink 123GI, and the blue ink 123BI, which are solutionsfor forming the light emitting layers 123.

For the purpose of simplifying the description, the three color inks areapplied in order by the following application method. First, one of theinks is applied over substrates. Then, another one of the inks isapplied over the substrates. Lastly, the last one of the inks is appliedover the substrates.

The following describes an application process of one of the three colorinks, namely, the red ink onto substrates as a representative. Note thatthe red ink is applied to one of each three regions that are adjacent toeach other in the X-direction.

According to this application method, the ink is applied to the regionsof a lattice shape defined by the insulating sublayers 122X and 122Y.Specifically, as shown in FIG. 15, the substrate 100 x is placed suchthat the longitudinal direction and the width direction of the subpixels100 se respectively coincide with the Y-direction and the X-direction.The ink discharge device performs ink application by, while scanning inthe X direction with use of an ink jet head 622, discharging ink fromdischarge ports 624 d 1 of the ink jet head 622 toward arrival targetsthat are set in the regions of a lattice shape which are defined by theinsulating sublayers 122X and 122Y. In FIG. 15, the red subpixels 100 seinclude arrival target positions onto which the red ink is to beapplied.

Note that, among the discharge ports 624 d 1 of the ink jet head 622,only discharge ports 624 d 1, which pass above regions between each twoadjacent insulating sublayers 122X, are used. Meanwhile, discharge ports624 d 1 (indicated by sign x in FIG. 15), which pass above theinsulating sublayers 122X, are always unused. According to the exampleshown in FIG. 15, seven arrival targets are set in each of the regionsof the subpixel, and ink droplets are discharged from seven dischargeports 624 d 1.

After application of the one of the three color inks over the substrate100 x completes, application of another one of the inks is performedover the same substrate 100 x, and lastly application of the last one ofthe inks is performed above the same substrate 100 x. This applicationprocess of the three color inks is repeatedly performed for each of thesubstrates 100 x.

Alternatively, the three color inks may be applied in order in thefollowing manner. Specifically, when application of one of the inksabove all of the substrates 100 x is complete, the application processmay be repeatedly performed to apply another one of the inks onto thesubstrates 100 x, and then apply the other ink onto the substrate 100 x.

(7) Formation of Electron Transport Layer 124, Counter Electrode Layer125, and Sealing Layer 126

An electron transport layer 124 is formed with the vacuum depositionmethod or the like. Then, a counter electrode layer 125 and a sealinglayer 126 are formed in the stated order so as to cover the electrontransport layer 124 (FIGS. 10C and 13D). The counter electrode layer 125and the sealing layer 126 are formed with the CVD method, the sputteringmethod, or the like.

(8) Formation of CF Substrate 131

The following exemplifies a process of manufacturing a CF substrate 131with reference to the figures. FIGS. 16A-16F are schematiccross-sectional views of the organic EL display panel 10 duringmanufacture, showing manufacturing of the CF substrate 131.

A light shielding layer paste 129R is prepared by dispersing in asolvent a material of a light shielding layer 129 mainly containingultraviolet curable resin (for example, ultraviolet curable acrylicresin). The light shielding layer paste 129R is applied onto one ofsurfaces of a transparent upper substrate 130 (FIG. 16A).

The applied light shielding layer paste 129R is dried and the solvent isvaporized to a certain degree. Then, a pattern mask PM1 havingpredetermined openings is overlaid above the light shielding layer paste129R, and ultraviolet irradiation is performed on the pattern mask PM1(FIG. 16B).

Then, the light shielding layer paste 129R, which has been applied andfrom which the solvent has been removed, is fired, and development isperformed for removing the pattern mask PM1 and uncured parts of thelight shielding layer paste 129R. Then, the light shielding layer paste129R is cured. As a result, the light shielding layer 129 having arectangular cross section is complete (FIG. 16C).

Next, a paste 128R is prepared by dispersing in a solvent a material ofcolor filter layers 128 (for example, color filter layers 128G) mainlycontaining an ultraviolet curable resin component. The paste 128R isapplied to the surface of the upper substrate 130 on which the lightshielding layer 129 is formed. The solvent is removed to a certaindegree, and then a predetermined pattern mask PM2 is overlaid above thepaste 128R and ultraviolet irradiation is performed on the pattern maskPM2 (FIG. 16D).

Then, development is performed for removing the pattern mask PM2 anduncured parts of the paste 128R, and the paste 128R is cured. As aresult, the color filter layers 128G are complete (FIG. 16E).

Color filter layers 128R and 128B are also formed by similarly repeatingthe processes in FIGS. 16D and 16E on color filter materials of the Rand B colors. Note that any commercially available color filter productsmay be used instead of using the paste 128R.

This completes the CF substrate 131.

(9) Bonding of CF Substrate 131 and Rear Panel

The following describes a bonding process of the CF substrate 131 and arear panel in manufacturing the display panel 10. FIGS. 11A and 11B areschematic cross-sectional views taken along a line at the same positionas the line A1-A1 in FIG. 4B. FIGS. 14A and 14B are schematiccross-sectional views taken along a line at the same position as theline B1-B1 in FIG. 4B.

First, a material of a bond layer 127 mainly containinglight-transmissive ultraviolet curable resin is applied to the rearpanel, which is composed of the substrate 100 x and the layers rangingfrom the pixel electrode layers 119 to the sealing layer 126 (FIGS. 11Aand 14A). The light-transmissive ultraviolet curable resin is forexample acrylic resin, silicone resin, or epoxy resin.

Subsequently, ultraviolet irradiation is performed on the appliedmaterial such that the CF substrate 131 and the rear panel are bonded toeach other while positions relative to each other are maintained. Atthis time, intrusion of gas therebetween needs to be prevented. Then,the CF substrate 131 and the rear panel are fired. This completes asealing process (FIGS. 11B and 14B).

The display panel 10 is complete through the above processes.

5. Effect of Display Panel 10

5.1 Display Function

As described above, the insulating layer 122 has, in each of thesubpixels 100 se, the elongated first openings 122 z 1 and 122 z 2,which extend in the column direction and are arranged in the rowdirection, and the second openings 122 u, which are shorter in thecolumn direction than the first openings 122 z and are lined up adjacentto the first openings 122 z. Organic functional layers including thehole injection layers 120, the light emitting layers 123, and so on areformed in the first openings 122 z. The hole injection layers 120 areexposed in the first openings 122 z and the second openings 122 u so asto be in contact with the hole transport layers 121. This configurationallows electrical charge supply in these openings from the pixelelectrode layers 119 to the hole transport layers 121.

Light is emitted from only parts of the light emitting layers 123 towhich carriers are supplied from the pixel electrode layers 119, andaccordingly no electroluminescence of organic compound occurs in regionsof the light emitting layers 123 where the insulating layer 122 isprovided, which is made of an insulating material. Thus, light isemitted from only parts of the light emitting layers 123, positioned inthe openings 122 z and 122 u, where no insulating layer 122 is provided.These minimum rectangular regions including the openings 122 z and 122 uare the luminous regions 100 a. Regions other than the luminous regions100 a in the subpixels 100 se are the non-luminous regions 100 b. Inother words, the display panel 10 has the configuration in which thesubpixels 100 se are arranged in a matrix where the luminous regions 100a and the non-luminous regions 100 b alternate in the column direction,owing to the pixel electrode layers 119 layered on the substrate 100 xand the openings 122 z provided in the insulating layer 122.

Also, the openings 122 z and 122 u each have a predetermined trapezoidalcross section taken along the row direction whose width increasesupward. With this configuration, the light emitting layers 123efficiently emit light upward.

5.2 Test for Effect Check

The following describes the effects of the display panel 10. Theinventors performed a test with use of the display panel 10 in order tosuppress an insufficient ink spread in the pixels during a manufacturingprocess. The following provides comparative description of reflectors ofdisplay panels 10 relating to examples with a conventional reflector interms of light extraction efficiency and ink spread.

(1) Examples 1 and 2

An insulating layer 122 corresponding to a subpixel region 100 a of thedisplay panel 10 relating to Example 1 in plan view is the same as thatshown in FIG. 4B.

In each of the subpixels in the display panel 10 relating to Example 1,the insulating layer 122 has two first openings 122 z 1 and 122 z 2,which are elongated in the column direction, and second openings 122 u,which are lined up adjacent to the first openings 122 z 1 and 122 z 2.Specifically, nine second openings 122 u are provided in regularintervals in the Y-direction. A region including the nine secondopenings 122 u and the first openings 122 z 1 and 122 z constitutes aluminous region. The second openings 122 u have a width in the columndirection and a width in the row direction that are equal to each other(1:1). The first openings 122 z have a width in the column directionthat is 20 times a width in the row direction (20:1). The first openings122 z and the second openings 122 u have an equal width in the rowdirection.

In the display panel 10 relating to Example 1, the height of upper edges122 wb of a bar 122 w 1 between the first opening 122 z 1 and the secondopenings 122 u and a bar 122 w 2 between the first opening 122 z 2 andthe second openings 122 u is 60% to 70% of the height of an upper edge122Yb of the insulating sublayer 122Y.

In the display panel 10 relating to Example 2 compared with this, theheight of the upper edges 122 wb of the bars 122 w 1 and 122 w 2 areequal to the height of the upper edge 122Yb of the insulating sublayer122Y. The display panel 10 relating to Example 2 has the sameconfiguration as the display panel 10 relating to Example 1 other thanthe height of the bars 122 w 1 and 122 w 2.

(2) Light Extraction Efficiency

Luminance magnification of Examples 1 and 2 was calculated.

FIG. 17 shows calculated values of luminance magnification forsubpixels. The luminance magnification indicates a luminance value ofeach sample relative to that of planar subpixels of the same size withno reflector.

As shown in FIG. 17, Examples 1 and 2 both exhibit luminancemagnification of 1.47. It is true that the luminance magnification ofExamples 1 and 2 is lower than that of Sample A shown in FIG. 20, andspecifically its ratio is 1.47/1.6. However, the luminance magnificationof Examples 1 and 2 is higher than that of Sample B shown in FIG. 20,and specifically its ratio is 1.47/1.4. Accordingly, the luminancemagnification of Examples 1 and 2 is not low enough to damage effects ofthe reflector.

The reason why Examples 1 and 2 exhibit an improved light extractionefficiency compared with Sample B seems to be the second openings 122 ufunctioning as a preferable reflector with the width in the columndirection and the width in the row direction that are close in value toeach other.

(3) Ink Spread

Next, regarding the ink spread, the inventors performed a test offorming functional layers using inks of the same amount in order tomeasure an ink spread rate based on a ratio of an area of the functionallayers to an area of the subpixel region 100 a. FIG. 17 shows ameasurement result of the ink spread rate for the light emitting layersin the subpixels. As shown in FIG. 17, while Example 2 exhibits an inkspread rate of 75%, Example 1 exhibits an ink spread rate of 100%, whichis higher than Example 2.

This seems to be because of the following reason. In Example 1, thefirst opening 122 z has no bar that hinders the flow of the ink in thecolumn direction, and thus the ink easily flows in the column direction.Also, since the first openings 122 z are elongated and extend in thecolumn direction, air in the first openings 122 z easily flows in thecolumn direction, and thus does not hinder the flow of the ink so much.Furthermore, the height of the bars, which hinder the ink flow in therow direction, is low, and this facilitates the ink flow in the rowdirection. Thus, an ink spreads in the first openings 122 z in thecolumn direction, and then further spreads therefrom in the rowdirection. As a result, the ink spreads over the entire subpixel region100 a. This seems to be the reason why Example 1 exhibits an ink spreadrate higher than Example 2.

6. Modification

In the above embodiment, the display panels 10 is described. However,the present disclosure is not limited to the above embodiment except theessential characteristic compositional elements thereof. The followingdescribes a modification of the display panel 10 as an example of suchan embodiment, with reference to FIGS. 18A-18H.

(1) Connection Grooves 122 v 1 Provided in Non-Luminous Regions so as tobe Communicated with First Openings 122 z in Adjacent Subpixels inColumn Direction

In the modification of the display panel 10 as shown in FIG. 18A, aninsulating layer 122 has, in each of non-luminous regions 100 b, aconnection groove 122 v 1 having an upper opening and a bottom. Theconnection groove 122 v 1 is communicated with either first openings 122z 1 or 122 z 2 in subpixels adjacent to the non-luminous region 100 b inthe column direction. The display panel relating to the presentmodification has the same configuration other than the connection groove122 v 1 as that of the display panel 10 relating to the embodiment, andaccordingly its description is omitted here.

Also, the connection groove 122 v 1 may be provided in plural as shownin FIG. 18B. Specifically, in plan view, connection grooves 122 v 1 and122 v 2 may be provided that are respectively communicated with thefirst openings 122 z 1 and 122 z 2 in the column direction.

The connection groove 122 v 1 with this configuration increases the flowof an ink, which contains organic compound as materials of the lightemitting layers 123, in the column direction, thereby to suppressvariation in application amount of the ink between the subpixels. As aresult, it is possible to suppress luminance unevenness caused byvariation in film thickness of the light emitting layers 123 betweenluminous regions 100 a in the subpixels.

Although organic functional layers, which include hole injection layers120, the light emitting layers 123, and so on, are formed also in theconnection grooves 122 v 1, the hole injection layers 120 are notexposed in the connection grooves 122 v 1 of the insulating layer 122,which have a groove-shaped cross section and have upper openings andbottoms. Thus, electrical charge supply from the pixel electrode layers119 to the hole transport layers 121 is not performed in the connectiongrooves 122 v 1. Light is emitted from only parts of the light emittinglayers 123 to which carriers are supplied from the pixel electrodelayers 119, and accordingly no electroluminescence of organic compoundoccurs in regions of the light emitting layers 123 where the insulatinglayer 122 is provided, which is made of an insulating material.

(2) Grooves with Increased or Decreased Area

The connection grooves 122 v 1 and 122 v 2 in each of the non-luminousregions 100 b may have an increased area and a decreased area asrespectively shown in FIGS. 18A and 18B. Moreover, the connectiongrooves 122 v 1 and 122 v 2 whose area increases or decreases may beseparated from the first openings 122 z by a distance 6 in the columndirection.

(3) Bridging Grooves 122 v 0 Communicated with First Openings 122 z inRow Direction

As shown in FIG. 18C, the grooved portions 122 v may include, for eachof the non-luminous regions 100 b, bridging grooves 122 v 0 and aconnection groove 122 v 1, in plan view. The bridging grooves 122 v 0are communicated with the first openings 122 z 1 and 122 z 2 in the rowdirection, and the connection groove 122 v 1 is communicated between thebridging grooves 122 v 0 in the column direction. Also, as shown in FIG.18D, the bridging groove 122 v 0 shown in FIG. 18C may have an increasedarea that is equal to the entire area of the non-luminous region 100 b.

The bridging grooves 122 v 0 with these configurations further increasethe flow of the ink, which contains organic compound as materials of thelight emitting layers 123, between the first openings 122 z and thesecond openings 122 u in the row direction, thereby to suppressvariation in application amount of the ink in each subpixel. As aresult, it is possible to suppress luminance unevenness caused byvariation in film thickness of the light emitting layers 123 between theluminous regions 100 a in the subpixels.

(4) Openings in Different Number

In the above modification of the display panel 10, the insulating layer122 has, above each of the pixel electrode layers 119, the two elongatedfirst openings 122 z 1 and 122 z 2, the second openings 122 u, and theconnection groove 122 v with an upper opening and a bottom. The firstopenings 122 z 1 and 122 z 2 extend in the column direction and arearranged in the row direction. The second openings 122 u are shorter inthe column direction than the first openings 122 z 1 and 122 z 2 and arelined up adjacent to the first openings 122 z 1 and 122 z 2. Theconnection groove 122 v is communicated with either the first opening122 z 1 or 122 z 2.

Alternatively, the number of the first openings 122 z and the number ofthe rows of the second openings 122 u each may be modified.Specifically, a single first opening 122 z and a single row of thesecond openings 122 u may be provided (FIG. 18E). Further alternatively,a single first opening 122 z and two rows of the second openings 122 uwith the first opening 122 z therebetween may be provided (FIG. 18F).Yet alternatively, two first openings 122 z and three rows of the secondopenings 122 u may be provided such that each first opening 122 z issandwiched between two adjacent rows of the second openings 122 u (FIG.18G).

(5) Second Openings 122 u with Different Size

As shown in FIG. 18H, second openings 122 t may be provided byincreasing the size of the second openings 122 u shown in FIG. 18A. Thesecond openings 122 t are communicated with the first openings 122 z 1and 122 z 2 at row-directional ends 122 ta thereof.

With this configuration, it is possible to further increase the flow ofthe ink in the row direction via the second openings 122 u, thereby tosuppress variation in application amount of the ink in each subpixel.This suppresses luminance unevenness caused by variation in filmthickness of the light emitting layers 123 between the luminous regions100 a in the subpixels.

(6) Connection Grooves 122 v and First Openings 122 z with the SameCross-Sectional Profile

According to the configurations shown in FIGS. 18A, 18B, 18E, 18F, and18H, the upper width of the connection grooves 122 v in the rowdirection is equal or substantially equal to the upper width of thefirst openings 122 z in the row direction. Also, the width of theconnection grooves 122 v in the column direction is 1 μm to 8 μm. Inother words, the cross-sectional profiles of the first openings 122 ztaken along the row direction are uniform in the column direction orcontinuously vary along the column direction. With this configuration,the connection grooves 122 v have substantially the same cross-sectionalprofile as that of the first openings 122 z, and thus it is possible toprevent the connection grooves 122 v from influencing ink retentionability at the end edges of the first openings 122 z. This furtheruniformly retains the ink at the end edges of the first openings 122 z,and suppresses variation of factors that influence the ink retentionability in application of the ink containing organic compound asmaterials of the light emitting layers 123 during the manufacturingprocess. As a result, the ink is retained uniformly in the luminousregions 100 a of the subpixels, and thus variation in film thickness ofthe light emitting layers 123 is reduced to further suppress luminanceunevenness in each subpixel.

Other Modifications

Although the display panel 10 has been described in the aboveembodiment, the present disclosure also includes, for example, anembodiment obtained through various types of modifications which couldbe conceived of by one skilled in the art to the above embodiment, anembodiment obtained through any combination of the compositionalelements and the functions in the above embodiment without departingfrom the spirit of the present disclosure, and so on. The followingdescribes modifications of the display panel 10 as examples of such anembodiment.

(1) In the display panel 10, the light emitting layers 123 arecontinuous in the column direction above the row banks. Alternatively,the light emitting layers 123 may not be continuous for the entirepixels above the row banks. Even with this configuration, it is possibleto improve the light extraction efficiency.

(2) In the display panel 10, the light emitting layers 123 of thesubpixels 100 se, which are arranged in the gaps 522 z between thecolumn banks 522Y adjacent in the row direction, each emit light of acolor different from adjacent one. Meanwhile, the light emitting layers123 of the subpixels 100 se, which are arranged between the insulatingsublayers 122X adjacent in the column direction, emit light of the samecolor. Alternatively, the light emitting layers 123 of the subpixels 100se, which are adjacent in the row direction, may emit light of the samecolor, and the light emitting layers 123 of the subpixels 100 se, whichare adjacent in the column direction, each may emit light of a colordifferent from adjacent one. Further alternatively, the light emittinglayers 123 of the subpixels 100 se, which are adjacent in the rowdirection, each may emit light of a color different from adjacent one,and the light emitting layers 123 of the subpixels 100 se, which areadjacent in the column direction, each may emit light of a colordifferent from adjacent one. Even with this configuration, it ispossible to improve the light extraction efficiency.

(3) Others

The display panel 10 relating to the above embodiment includes thesubpixels 100 se of the three colors of red, green, and blue. However,the present disclosure is not limited to this. For example, the lightemitting layers may be ones emitting light of a single color, orrespective ones emitting light of four colors of red, green, blue, andyellow.

Also, the unit pixels 100 e are arranged in a matrix in the aboveembodiment. However, the present disclosure is not limited to this. Theeffect of the present disclosure is exhibited also for the configurationin which in the case for example where an interval of the pixel regionis one pitch, the pixel region is shifted in the column direction byhalf pitch between adjacent gaps. In display panels with increasing highresolution, since it is difficult to visually discriminate some shift inthe column direction, an irregular film thickness in a straight (orstaggered) shape with a certain width is viewed as a stripe-shaped one.Thus, in such a case, it is possible to improve the display quality ofthe display panels by suppressing an irregular luminance in a staggeredshape such as described above.

Also, the display panel 10 includes the pixel electrode layers 119 eachof which are provided between every two of all the gaps 522 z. However,the present disclosure is not limited to this. For example, some of thegaps 522 z may not have the pixel electrode layer 119 therebetween inorder to form a bus bar or the like.

Moreover, the display panel 10 includes the color filter layers 128 thatare provided above the gaps 522 z corresponding to the subpixels 100 seof the R, G, and B colors. Alternatively, the exemplified display panel10 may have a configuration in which the color filter layers 128 are notprovided above the gaps 522 z.

Also, in the above embodiment, the hole injection layers 120, the holetransport layers 121, the light emitting layers 123, and the electrontransport layer 124 are provided between each of the pixel electrodelayers 119 and the counter electrode layer 125. However, the presentdisclosure is not limited to this. For example, only the light emittinglayers 123 may be provided between each of the pixel electrode layers119 and the counter electrode layer 125, without providing the holeinjection layers 120, the hole transport layers 121, and the electrontransport layer 124. Alternatively, hole injection layers, a holetransport layer, an electron transport layer, an electron injectionlayer, and so on may be included, or some or all of these layers may besimultaneously included, for example. Moreover, all of these layers donot need to be made of organic compound, and alternatively some of thelayers may be made of inorganic substance or the like. Furthermore, thehole injection layers 120, the hole transport layers 121, and theelectron transport layer 124 may be formed using a dry deposition methodsuch as the vacuum deposition method, an electron beam depositionmethod, the sputtering method, a reactive sputtering method, an ionplating method, and a chemical vapor deposition method. Also, in thecase where the hole injection layers 120 and the hole transport layers121 are formed using the dry deposition method, the pixel electrodelayers 119, the hole injection layers 120, the hole transport layers121, the insulating layer 122, and the light emitting layers 123 may belayered in the stated order.

Also, in the above embodiment, the light emitting layers 123 are formedusing a wet deposition method such as the printing method, the spincoating method, and the ink jet method. However, the present disclosureis not limited to this. For example, the dry deposition method may beused such as the vacuum deposition method, the electron beam depositionmethod, the sputtering method, the reactive sputtering method, the ionplating method, and the chemical vapor deposition method. Moreover, aknown material may be appropriately adopted for the materials of thecomponents.

Also, in the above embodiment, the pixel electrode layers 119 as anodesare provided in the lower part of the organic EL element unit so as tobe connected with the source electrodes of the TFTs. Alternatively, thecounter electrode layer and the anodes may be provided respectively inthe lower part and the upper part of the organic EL element unit. Inthis case, the cathode that is provided in the lower part is connectedwith the drain electrodes of the TFTs.

Also, the two transistors Tr₁ and Tr₂ are provided for each subpixel 100se in the above embodiment. However, the present disclosure is notlimited to this. For example, one transistor may be provided for eachsubpixel, or three or more transistors may be provided for eachsubpixel.

Furthermore, an EL display panel of the top-emission type is exemplifiedin the above embodiment. However, the present disclosure is not limitedto this. For example, the present disclosure may be applied to a displaypanel of a bottom-emission type. In this case, the configurations of thecomponents may be appropriately modified.

Also, in the above embodiment, the display panel 10 is an active-matrixdisplay panel. However, the present disclosure is not limited to this.For example, the display panel 10 may be a passive-matrix display panel.Specifically, pairs of a linear electrode, which is parallel to thecolumn direction, and a linear electrode, which is parallel to the rowdirection, may be provided such that each pair of the electrodessandwich the light emitting layer 123 therebetween. In this case, theconfigurations of the components may be appropriately modified. Althoughthe substrate 100 x in the above embodiment includes the TFT layer, thesubstrate 100 x does not necessarily need to include the TFT layer asseen in the above example of the passive-matrix display panel.

<<Supplements>>

The embodiment described above shows a specific preferred example of thepresent disclosure. The numerical values, the shapes, the materials, thecomponents, the arrangement and connection status of the components, theprocesses, the order of the processes, and so on described in the aboveembodiment are just examples, and do not intend to limit the presentdisclosure. Also, processes among the components in the embodiment,which are not described in the independent claims representing the mostgeneric concept of the present disclosure, are explained as arbitrarycomponents of a more preferred embodiment.

Furthermore, the order of performing the above processes isexemplification for specifically describing the present disclosure, andthe processes may be performed in an order different from the above one.Moreover, part of the above processes may be performed simultaneously(in parallel) with other process.

Also, the components shown in the figures in the above embodiment arenot necessarily drawn to scale for easy understanding of the presentdisclosure. Furthermore, the present disclosure is not limited by thedescription of the above embodiment, and may be appropriately modifiedwithout departing from the scope of the present disclosure.

Moreover, at least part of the functions of the above embodiment andmodifications may be combined with each other.

Furthermore, the present disclosure also includes embodiments obtainedthrough various types of modifications that could be conceived of by oneskilled in the art to the above embodiment.

INDUSTRIAL APPLICABILITY

The organic EL display panel and the organic EL display device relatingto the present disclosure are broadly utilizable to devices such astelevision sets, personal computers, and mobile phones, or other varioustypes of electrical devices having display panels.

REFERENCE SIGNS LIST

-   -   1 Organic EL display device    -   10 Organic EL display panel    -   100 Organic EL element    -   100 e Unit pixel    -   100 se Subpixel    -   100 a Luminous region    -   100 b Non-luminous region    -   100 x Substrate (TFT substrate)    -   100 p Lower substrate    -   101, 102 Gate electrode    -   103 Gate insulating layer    -   104, 105 Channel layer    -   106 Channel protection layer    -   107, 110 Source electrode    -   108, 109 Drain electrode    -   111 Source lower electrode    -   112 Drain lower electrode    -   113 Contact plug    -   116 Passivation layer    -   117 Connection electrode layer    -   118 Interlayer insulating layer    -   119 Pixel electrode layer    -   119 a 1, 119 a 2, 119 a 3, 119 a 4 Outer edge    -   119 b Contact region (contact window)    -   119 c Connection concave part    -   120 Hole injection layer    -   121 Hole transport layer    -   122, 122X, 122Y Insulating layer    -   122 z Opening    -   122 w Bar    -   123 Light emitting layer    -   124 Electron transport layer    -   125 Counter electrode layer    -   126 Sealing layer    -   127 Bond layer    -   128 Color filter layer    -   129 Light shielding layer    -   129X Row light shielding sublayer    -   129Y Column light shielding sublayer    -   130 Upper substrate    -   131 CF substrate    -   522Y Column bank    -   522 z Gap    -   622 Ink jet head    -   624 Discharge port    -   EL EL element unit    -   Tr₁ Drive transistor    -   Tr₂ Switching transistor    -   C Capacitance

1. An organic electroluminescence (EL) display panel including pixelsarranged in a matrix of rows and columns, the organic EL display panelcomprising: a substrate; pixel electrode layers that are made of alight-reflective material and are arranged on the substrate in thematrix; an insulating layer that is provided above the substrate and thepixel electrode layers; organic functional layers that are providedabove the pixel electrode layers; and a light-transmissive counterelectrode layer that is provided above the organic functional layers,wherein the insulating layer has a first opening and second openings foreach of the pixel electrode layers, the first opening being elongated ina column direction, the second openings each being shorter than thefirst opening in the column direction and being lined up adjacent to thefirst opening, and the organic functional layers include light-emittinglayers in which organic electroluminescence occurs in the first openingand the second openings.
 2. The organic EL display panel of claim 1,wherein for each of the pixels, an upper edge of a wall of each of thesecond openings that is away from an outer edge of the pixel in a rowdirection is lower in height than one of an upper edge of a wall of thefirst opening and an upper edge of a wall of each of the second openingsthat are nearest the outer edge in the row direction.
 3. The organic ELdisplay panel of claim 1, wherein for each of the pixels, one of a wallof the first opening and a wall of each of the second openings that areaway from an outer edge of the pixel in a row direction is larger ingradient than one of a wall of the first opening and a wall of each ofthe second openings that are nearest the outer edge in the rowdirection.
 4. The organic EL display panel of claim 1, wherein theinsulating layer further has a third opening for each of the pixelelectrode layers, the third opening being elongated in the columndirection, the second openings are disposed between the first openingand the third opening in a row direction, an upper edge of a wall of thefirst opening that is adjacent to the second openings in the rowdirection is lower in height than an upper edge of a wall of the firstopening that faces the wall of the first opening that is adjacent to thesecond openings in the row direction, and an upper edge of a wall of thethird opening that is adjacent to the second openings in the rowdirection is lower in height than an upper edge of a wall of the thirdopening that faces the wall of the third opening that is adjacent to thesecond openings in the row direction.
 5. The organic EL display panel ofclaim 4, wherein the wall of the first opening that faces the adjacentwall of the first opening is smaller in gradient than the wall of thefirst opening that is adjacent to the second openings, and the wall ofthe third opening that faces the adjacent wall of the third opening issmaller in gradient than the wall of the third opening that is adjacentto the second openings.
 6. The organic EL display panel of claim 4,wherein the first opening and the third opening have a width in the rowdirection that increases upward, and the second openings have a width inthe row direction and a width in the column direction that increaseupward.
 7. The organic EL display panel of claim 6, further comprising abond layer that is provided above the counter electrode layer and has arear surface that is convex along the first, second, and third openings,and when refractive indices of the bond layer and the insulating layerare represented by n₁ and n₂, respectively, the following relationshipsare satisfied:1.1≤n ₁≤1.8  (Formula 1); and|n ₁ −n ₂|≥0.20  (Formula 2).
 8. The organic EL display panel of claim6, wherein when depth, upper width in the row direction, and lower widthin the row direction of the first, second, and third openings arerepresented by D, W_(h), and W₁, respectively, the followingrelationships are satisfied:0.5≤W ₁ /W _(h)≤0.8  (Formula 3); and0.5≤D/W ₁≤2.0  (Formula 4).
 9. The organic EL display panel of claim 1,wherein in plan view, regions of the substrate where the first andsecond openings are provided are luminous regions in the pixels, regionsof the substrate that are each arranged between two adjacent of theluminous regions in the column direction are non-luminous regions in thepixels, and the insulating layer further has, in each of thenon-luminous regions, a grooved portion with an upper opening and abottom, the grooved portion being communicated with the first openingsin two pixels that are adjacent to the non-luminous region in the columndirection.
 10. The organic EL display panel of claim 4, wherein in planview, regions of the substrate where the first and second openings areprovided are luminous regions in the pixels, regions of the substratethat are each arranged between two adjacent of the luminous regions inthe column direction are non-luminous regions in the pixels, theinsulating layer further has, in each of the non-luminous regions, agrooved portion with an upper opening and a bottom, the grooved portionbeing communicated with the first openings in two pixels that areadjacent to the non-luminous region in the column direction, and theorganic functional layers are in contact with the pixel electrode layersin the first, second, and third openings, and are separated from thepixel electrode layers in the grooved portions.